JPS58215971A - Parallel operation circuit for switching power source - Google Patents

Abstract

PURPOSE:To prevent an erroneous operation of a switching power source by inserting a diode to a reference voltage line of a drive circuit and a control circuit of switching means, thereby blocking a current of the drive circuit to flow the control circuit when a plurality of switching power sources are operated in parallel. CONSTITUTION:A diode 4 is connected in polarity as shown to a 0V line between a drive circuit 2 and a control circuit 3 of a switching power source SWRG-1. The diode 4 is similarly connected to a switching power source SWRG- 2. Accordingly, a drive current ID flowed to the drive circuit 2 does not flow to the zero volt line of the control circuit 3 for the diode 4, but flows to a zero voltage line N of an auxiliary power source. Thus, no noise is produced, and no erroneous operation occurs in the control circuit 3.

Description

Detailed Description of the Invention (1) Technical Field of the Invention The present invention relates to a switching power supply device, and in particular to a parallel switching power supply device that enables accurate control even when a plurality of switching power supplies are operated in parallel. Regarding the driving circuit.

(2) Background of the Technology A switching power supply device if using a switching element such as a transistor, for example, is widely used in data processing devices and the like because of its low heat generation and high efficiency.

Recently, data processing equipment has become larger, or IO and LS are used to configure data processing equipment to perform complex data processing.
The number of I's has increased, and as a result, a large capacity power supply with low torque and large current has become necessary.

However, transistors that are commonly used as switching elements have a limited switching capacity, and when constructing a large-capacity power supply, it is necessary to use a plurality of switching power supplies connected in parallel.

(3) Prior art and problems Therefore, when constructing a large-capacity switching power supply, for example, as shown in FIG.
1.5WR-22 connected in parallel.

The desired voltage and current will be supplied to the load LOD.

In the example shown in Fig. 1, two switching power supplies SW-1
, 5WR-2 are connected in parallel, but depending on the type of load, an even larger number of switching power supplies may be connected in parallel.

Here, the switching power supply SW-1 includes a transformer 1, a drive circuit 2. Control circuit 3 and switching transistor Q
'*U diode DI* D2, smoothing inductance L, smoothing capacitor C, etc. are configured, and the switching power supply SW 几-2 is also the switching power supply 5WR-1.
It is configured in the same way.

The drive circuit 2 is provided with a drive transistor Q2,
A control circuit 3 controls turning on and off of this drive transistor Q2. At this time, the control circuit 3 connects the terminal voltage of the capacitor C, which outputs the rectified voltage, to the resistor R.
, 1, a voltage divided by z, that is, a voltage proportional to the rectified output, is transmitted.

According to this rectified output voltage, drive transistor Q
Controls the on time of 2. In other words, when the rectified output voltage is smaller than the set value, the transistor Q! Increase the base voltage application time to turn on. As a result, transistor Q2 remains on for a long time, and an on-current flows between the collector and emitter due to the auxiliary power supply. In proportion to this, the drive circuit 2 is driven by the transistor Q1.
Since the base voltage for controlling the on-state of the transistor Q1 is output for a long time, the on-time of the transistor Q1 that switches the main power supply becomes long. As a result, the output voltage time of the secondary winding of the transformer 1 is also longer υ, and its rectified output voltage is 0.

Conversely, if the rectified output voltage is greater than the set value.

The control circuit 3 controls the transistor Q! so that the on time of the transistor Ql is shortened. of? Since ilU is controlled, control is performed so that the rectified output voltage becomes small and approaches the set value.

However, in the past, as shown in Figure 1, when several +JI switching power supplies are connected in parallel, the pot output voltage is not controlled as expected, resulting in a malfunction.

In this case, there is a problem that each switching power supply works normally when used alone, but when connected in parallel, it malfunctions. Various studies were conducted to improve this problem, but the cause of the problem was unknown, so this problem did not occur. could not be resolved.

The inventors of the present invention conducted intensive research to find the cause of this problem and found that the malfunction occurs due to the following reasons.

That is, as shown in switching power supply SW-1 in Fig. 1, when the drive transistor Qz is turned on, the drive current ID flowing from the auxiliary power supply through its collector base flows through the zero volt line N of the auxiliary power supply. However, a part ID' of this drive current ID is connected to the zero volt line of the control circuit 3 - the zero volt line of the load LOD - the control of the switching power supply SW 几-2, as shown by the dashed line. This will flow through the zero volt line of the circuit, the zero volt line of the drive circuit, and the zero volt line of the auxiliary power supply, and as a result, noise will ride on the zero volt line of the control circuit 3, causing the control circuit 3 to malfunction. In this case, part or all of the drive current from multiple connected switching power supplies flows into the zero volt line of its own control circuit or other control circuits, resulting in the generation of complex noise. The present inventors have elucidated the cause of the malfunction.

(4) Purpose of the Invention As described above, the purpose of the present invention is to provide a parallel operation circuit for switching power supplies that can perform switching operations accurately without causing malfunctions when a plurality of switching power supplies are connected in parallel. It is.

(5) Structure of the Invention In order to achieve this object, the parallel operation circuit for a switching power supply of the present invention includes a switching means for turning on and off the main power supply, a drive circuit for driving the switching means, and a drive circuit for driving the switching means. In a switching power supply device equipped with a control circuit that controls the current of the drive circuit, a diode is inserted in the reference potential line between the drive circuit and the control circuit of the switching means, so that when a plurality of switching power supply devices are operated in parallel, the current of the drive circuit is controlled. The feature is that the current is prevented from flowing into the circuit.

(6) Examples of the invention An embodiment of the present invention will be described based on FIG.

In the figure, the same reference numerals as in Fig. 1 indicate the same parts, and SW 几G-1
, 8W90-2 correspond to switching power supplies 5WR-1 and SW-2 connected in parallel, respectively. A diode 4 is connected to the OV line between the drive circuit 2 and the control circuit 3 of the switching power supply 5WRG-1 with the polarity shown. Similarly, a diode 4 is connected to the switching power supply 5WRG-2. The drive circuit 2 and control circuit 3 operate in exactly the same manner as in FIG.

Therefore, the drive current ■D flowing through the drive circuit 2 does not flow to the zero volt line of the control circuit 3 because of the diode 4, but instead flows to the zero volt line N of the auxiliary power supply.
As a result, the above-mentioned noise does not occur, and the control circuit 3 does not malfunction.

In the embodiment shown in FIG. 2, an example in which two switching power supplies are used has been described, but the switching power supplies are of course not limited to this, and can be appropriately selected depending on the load.

(7) Effects of the Invention According to the present invention, noise generation in the control circuit based on the drive current is suppressed due to the diode installed in each switching power supply, so the control circuit does not malfunction as in the conventional case. do not have. Therefore the control circuit works properly.

Switching power supplies can be controlled accurately.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram of a conventional switching power supply parallel operation circuit, and FIG. 2 is a configuration diagram of an embodiment of the present invention. In the figure, l is a transformer, 2 is a drive circuit, 3 is a control circuit, 4
is a diode, SW 几-1, SW 几-2゜5WRG-
1,5WRG-2 are respectively switching power supplies +Q”
is a switching transistor, 9-fold is a drive transistor, Dl and C are rectifying diodes, L is a smoothing intalitance, C is a smoothing capacitor, R1 and 2 are resistors, and N is the zero-volt line of the auxiliary power supply. Patent applicant Fujitsu Ltd. agent Patent attorney Akira Yamatani 1st year 2nd year

Claims (1)

[Claims] (1) In a switching power supply device comprising a switching means for turning on and off the main power supply, a drive circuit for driving the switching means, and a control circuit for controlling the drive circuit, the drive circuit and the control circuit of the switching means are connected to each other. 1. A parallel operation circuit for a switching power supply, characterized in that a diode is inserted in a reference potential line to prevent current from the drive circuit from flowing to a control circuit when a plurality of switching power supply devices are operated in parallel.